Personal care products include absorbent articles like diapers, training pants, incontinence devices, feminine hygiene products and the like. These products are designed to absorb and contain body exudates and are generally single-use or disposable items which are discarded after a relatively short period of use--usually a period of hours--and are not intended to be washed and reused. Such products are placed against or in proximity to the wearer's body to absorb and contain various exudates discharged from the body. All of these products typically include a liquid permeable bodyside liner or cover, a liquid impermeable outer cover or backsheet, and an absorbent structure disposed between the bodyside liner and outer cover. The liquid impermeable outer cover may be breathable, i.e., permeable to water vapor.
It has been found that urination can occur at rates as high as 15 to 20 milliliters per second and at velocities as high as 280 centimeters per second. The volume of urine released per occurrence can vary from about a nominal amount to about 100 ml. It's important for the absorbent article to rapidly uptake liquid to avoid excessive pooling of liquid on the body-facing surface of the bodyside liner in order to avoid leakage. Even if absorbed, however, any liquid in the article contributes to the overall humidity near the wearer' skin, causing discomfort and potential skin health problems due to skin hydration.
The problem of excessive humidity near the skin in an absorbent article has been addressed in the art through a number of means. U.S. Pat. No. 5,137,525 for example, uses mechanical means to increase airflow in the article. Breathable outer covers allow air and water vapor diffusion and have been mentioned previously. Osmotic agents have been investigated for use in personal care products to a minor extent. U.S. Pat. No. 5,108,383 to Lloyd White, dated Apr. 28, 1992, for example, discusses the use of materials such as sodium chloride, sugars and other water soluble salts as osmotic promoters in diapers and the like. The agent is enclosed in a film packet or bag that is placed in the article to encourage the absorption of large quantities of liquid. White teaches that the packet, which could also include wood fluff and other absorbing materials, outer non-absorbing sheets, fasteners and the like, is placed in a composite structure designed to pick up and retain fluids. The osmotic agent does not leave the packet but encourages the flow of liquid into the packet by osmotic pressure so the packet functions like a layer of superabsorbent, absorbing large volumes of fluid.
Despite these attempts, the need exists for further improvement in the reduction of skin hydration within absorbent articles. In particular, there is a need for agents that can remove water from the skin or reduce water absorption into the skin. The present invention provides for such reduced skin hydration within an ab sorbent article. More particularly, the invention relates to absorbent articles that reduce the hydration of the skin by modifying osmotic pressure through the use of agents.